It is known to include antimony trioxide dispersions in various polyester and vinyl ester resins to provide flame retardancy properties to fiberglass or other articles containing the resins.
Nyacol Products Inc., assignee of the present application manufactures and sells a flame retardant additive, "NYACOL" APE1540, which is a dispersion of colloidal antimony pentoxide particles in a liquid isophthalic polyester resin. It can be substituted for the more common antimony trioxide in flame retardant resins containing bromine or chlorine to provide certain advantages over the trioxide. In this context, NYACOL APE1540 could aptly be called a quality control enhancer because the fine particles are nearly invisible, allowing in-process and final inspection with the same degree of confidence as non-flame retardant laminates, as distinguished from the trioxide which results in opaque laminates. Other advantages over antimony trioxide include ease of handling and incorporation in the resin component for the product to be protected, better penetration into the structure because the particles are not filtered by the fiberglass, and the fact that it is more chemically resistant than the trioxide.
While antimony pentoxide flame retardant additives such as described above provide distinct advantages over antimony trioxide in commercial applications for providing flame retardant properties to the article in which it is incorporated, to a greater or lesser extent it alters the cure characteristics of unsaturated polyesters and may provide less than optimum results.
Accordingly, the task of the present invention may be stated to be to provide antimony pentoxide in a usable form for polyesters, i.e. so that it will not alter the cure characteristics to provide the final product or otherwise adversely effect the quality of the product in which it is incorporated to provide flame retardant properties.